Gastric motility is poorly understood because standard manometric techniques are inadequate when assessing smooth muscle contraction. A new high frequency catheter-based ultrasound probe has produced high resolution intraluminal images of esophageal muscle in human subjects. We aim to correlate changes in antral muscle thickness using intraluminal ultrsound with electrical activity and intraluminal pressures in healthy subjects and those with gastroparesis to further define our understanding of gastric motility. We concluded from this study that HFIUS is a novel technique to evaluate antral contractility. HFIUS can detect antral contractions which are not detected manometrically. Antral contractions identified by HFIUS occur at a rate similar to the gastric slow wave.